Treatment of gas



April 25, 1933. POWELL 1,905,053

TREATMENT OF GAS Filed Aug. 5, 1951 I v INVENTOR.

F/fred/P. Do we//.

Patented Apr. 25, 1933 UNITED sr 'rs-s PATENTi A OFFICE mm a. rowan. or 'nLrzua-rn, m messy, assxenoa so an x'orraas cornew or nmwaim, a comma-Ion or namwm 01' GAS.

Application fled August 5, 1981, Serial Io. 555,210.

y invention has for further objects such rative advantages and results as other 0 obtain in the process and apparatus described and claimed herewith.

Manufactured fuel gases, such as coke oven gas, carburetted water gas and the like generally contain a considerable variety of unsaturated organic compounds, many of which have relatively low molecular weights and exert relatively high vapor pressures. Certain of these unsaturates exhibit a tendency to pol lneri'zeror oxidize into comunds of her molecular weight and ower vapor pressure under suitable condi-,

tions of tem rature, pressure, oxygen conp tent andmolsture content of the gas, etc., and such conditions are frequently encountered dang? gas distri' bution,

As a t, In many distributing stems these unsaturatef r zompounds which leave the gas manufacturing plant in the form of vapor or gas are more or less graduallyjconverted into compounds. inca able of remaining in the and these atter compounds condense in the formof a mist or nsoid which is characterized by ex! treme y small particle The particles have a tacky or y nature and'are frequently carried for considerable distances by the gas stream. The are generally d'eposited however when. 0 gas is subjected to drawing, asin passing through a small or narrow orifice or when the direction of flow of the gas suddenly 'changed. a

The gummy or rednous deposits thereby formed tend to build up, causing stoppages 50 of orifices in governors and the like, out

in the passage of the gas thro ties. It is 'believ ages of pilot flames, and other difliculties and inconveniences. The unsaturates tending to cause these troubles are known broadly as gum-formers or gum-forming compounds, and it is believed that several distinct grou of chemical comp'oandsare' at least partially included in tlul class. The particular compound or group of compounds which is most troublesome in any particular instance depends to some extent at least on I! the source and nature of the gas distributed andon its treatment prior to distribution.

In some instances it is believed-that benzenoid gum-formers, such as indene and st ne, are the chief sources of'gum trouble. 6 T at es ecially appears to be the case when 7 relativel; wet gases, such as carburetted water gas with a high condensible oil content, are distributed. Such gases exhibit the gum-forming tendency even when distribu'ted at substantially atmospheric pressure, and it isbelieved that the oil' particles condensed from the gas serve as nuclei for the condensation of formers or scrub them from the gas us making 'ble their pfilymerization or oxidation in the liquid ase. When characteristically gases," such ascoke oven s, are trans r alf tted and distributedat su antially atmospheric pressure deposits of gums and seldom if ever are formed even when known gum.- formers, such' as indene and styre are present. When coke oven gas or the e is comre'ssed prior to ton and/or distri- I ution, however, gum-formers condense durf th the distri ut' systemto orm esti mass or suspens o id previously described, and then de- I positt'o cause sto and other-difliculi 1 t olefines andespe cially the dior even tri-olefines, such as butadiene and cyclopentadiene, are among the chief causes of this type of trouble.

I have found that when coke oven or the like is compressed, and especially w it is compto p of 20 n ds or I more r squareinch, as is "1-. the case when the gas is to be transmi for any considerab e before distribution to light oil. e This oily mist then serves as a medium or known that. they i vapor phase liquid medium j is not present.- It follows thereforethat while oil mistsin gas are not I, in themselves iormation. (po

; not be .previousl scrubbed to thaleneand/or Usually'coke its seaweed-sen cooled in the usual I manner to remove the heat ofcompression, a

veryfine mist of oil is produced in the gas. Thllis due to the fact that the gas is sub- 'gtgnti'ally saturated with certain oils, usu-- all. oils having a hi h boiling point ran n or to its compression. These oils mayisd bbmg e a nucleus for. polymerization of gum-form ing constituents of'thegas the liquid phase. Even when the gum-formers are present .in v0 small quantities and are compounds of ow boiling point and high vapor pressure they are given an ogportug nity to pass. into" the liquidphase solving in' the condensed oil present-ass mist after compression and cooling of the gas.

y dis- ,The presence of this mist of oil in compressed gasis'favorable-to the polymerization of the gum-formers s'ince' -.it-.is well v lymerize readily when in 3- the liquidstate, either as ure-substances or insolutioninotheroils. n the other hand,

it is believed that there is less tendenc for gu'm-formers to polymerize in (or from :the

- when condensed oil or other gum-forming they make gumconditions su ,that no polymerization Y would occur if the mist werenot. present.

' I have'ffoundthat. gum-formation .in', gas

a is efiectivel prevented xbyremo" e-oil mistf-rom-t egas priorato'dis'tribution, an I'ghajve found-that this his most-'eficiently accomplished 'by 'e'lectrical era ly t from tar, ammonia, hydrogen sulphide, and other impurities The gas mayor may the gas distrr uting' When onis to beef under, pressure, a compressor withdraws the purified from-the holder and com 1t .to-the esired pressure, which onthe cider-s of20poundsper ua're'in or highs; ,The isthencooie' usually to :"s'u ntially mg removes the? of atmospheric rature.

or petroleum oils empllo ed a en'e.

or glow di 7 tion oroxidation. of gum-formers'containe'dprecipitated. M eriz'ation) possible underpolymerization under the 4 electrical td-ischarge,jas well as the-removalgrecilpitation. This precipitation is" ref-- e'last step'in the"treatinent o the, gas-prior to admitting it to the distribumg system or the transmissionhne, and .the treated isthereforeat least'substantially em mph- I the .like af ter purification fromtar, 'ammonia, etc., is sent to .a holder foistora until it is transmit- This ma be when a.

compression and frequently results ,m the con ens'ationi 'of waterand/oirhydr carbOn "*iconstituents 'from'the' {It also a; in. the' formationof the, oil. mist descr bed for example.

hereinabove. In the practice present invention 1' subject this cooled gas to the influence o .a silent electrical discharge or glow discharge in an'electrical. precipitator,'.

such as the, well known Cottrell precipitator, for-example' By this method the ob ectionable oilymist is removed, andthe gas can then be distributed .without causing depositsof gum or resin "in orifices orother devices employed in the distributing system.

A' large number of compounds present in fuel'gases exhibit the gum-forming tendency,-as previousl stated and some of these.

have relatively high boiling points, in the order of 200 (3., and 'correspond ngl. lower vapor pressures; -Such. compoun are more or less completely condensed as a mist. along with the heavy oils durin compressim and after cooling, and bei g present mum oily mist they are removed when the gas is' treated according to "theprocesaof' been founcithat sub my .present invention "Furthermore, it .has a jecting the Sales to the influence of the silent arge promotes the polymerizatherein as described .in a copending ap lica tion'ofW. -L. vShively, .SerialjNo. 55 -,994,I

of gum-formers and oil'condensed into a mist by compression and'cooling.-

.' The potential "required for preci itation J needy at the and/or. ,thepolyme s in an electrical recipitator canbeare that the i I I d t h ni invention contempla e I gum-formers .or' gums bya static mach1ne,--an induction c011, a high volta alternating .current. .merato'r- 0 sn ormer, or. a t mum of high i u; h

cells or a rectifier operating on: high potential direct current, such-as a battery 0 tentialv alternating. current.

' The amount. of"

t a pressure ofthe' treated in the di8-' tance between the surePof the gas the hi arg'er diameter; in 1a preciprtator of the Iihave found that the best rcusual below the flash-overpoint; or a int.

- tential was a 60,000 volts] is. applie t0 the ot a precipitator-havmg.tubes.t""

ference to sfla- I harge' electrode-and. the collecting electroderThe-greaterthe v I er-the -volt-' and similarlyzhigher voltages are re-.' with or icollectm' g electrod' es of tential' difi erence'fre iedin'hny particular case a 1; on us sults'arelobtainedi-when-the voltage' is just I as ac'eompanying drawing a eo type, as shown.

" electrode.

deposition of from tar,

- 6 into an a of practicing my improved process of treating coke oven gas and the like to prevent the gum 'or resin therefrom during distribution. In the drawing The sin le figure is a view partly in elevation and part1 in vertical section of apparatus suitable or thepractice of my present invention.

Fuel gas such. as coke oven gas or the like which has preferably been previously freed ammonia, h drogen sulphide and other impurities is wlthdrawn from a gas holder or other source a pipe 2 into a compressor 4. In this compressor the gas is comoressed' to the pressure required for transmission to the distributing system, which pressure may be of the order of pounds or more per square, inch.

The com ressed gas passes through a pipe her-cooler 8, which may be of the directtype but is preferably of'the indirect The gas passes downwardly through tubes 10 forming a part of the cooler and its heat is transferred to coolingwater which may be supplied to the space surrounding. the tubes through a pipe 11 and withdrawn. through a pipe 12. The gas is cooled to substantially atmospheric temperature, as is usual after compression.

Water or other condensate "formed by coolingthe compressed gas collects at the bottom ofthe cooler andmay be withdrawn through a pipe 14. The cooled gas containing a mist of conden ed heavy oil and/ or gum-formers as described hereinabove passes from the cooler through a pipe 16 and enters an electrical precip1tator 18.

The precipitator 18 contains a plurality of tubes 20 which serve ascollectmg electrodes. A wire, rod, or chain 22 passes through each of the tubes 20 in coaxial relation thereto and serves as a discharge The discharge electrodes are held in place by means of weights 24 and/ 'or' a grid 25 through which they'may pass orto which they may be attached. 'Potential is applied to the electrodes .from any suitable source such as a rectifier or a'transformer indicated diagrammatically at 27.

One of the secondary terminals of the transformer is. connected to'a bus bar 29 I supported on insulators 30 out of contact as indicated at with the shell of the precipitator. The electrodes 22 are connected to the bus bar 29. The other secondary terminal of the transformer may be grounded as indicated, and the precipitatorshell-is also grounded, 32. When the potential is applied to the electrodes a corona forms around the discharge electrode causing ionization of the gaswhich passes downwardly through the tubes 20. Solid or liquid par- !nist contained in the gas are thereby given a charge and carried (not shown) through selves.

It will. be obvious to those skilled in the.

present instance, are the tubes 20.

to the collecting electrodes which, in 'the' The gas is thereby freed from the oily mist I gas distributing system through which it may be delivered to the consumers without danger ofcausing deposits of gums and resins. Oil or the like precipitated from thegas in the manner described collects on the tubes 20 and flows therefrom to a sump near the bottom of the precipitator, from which it may be withdrawn through a pipe 37 for any desired disposal.

In the foregoing description the process of my present invention has been describedv with particular reference to its application to the treatment of gas at a pressure of 20 pounds per square inch or more. It is to be understood, however, that my invention is not limited in its application to the treatment of gas at any particular ressure but may be applied to any gas whic is substantially free from'tar and the like and which is benefited by the precipitation .of'oil mists therefrom.

It is also to be understood that the terms whereby gum-formers and the like are converted into harmless compounds which usually have higher molecular wei htand lower vapor art that certain changes can be made in the several steps of my process and the several parts of my apparatus without departing from the spirit of my invention, and it is related reactions pressure than the gumormers them my intention to 'cover in the claims such modifications as are included within the scopethereo f.

I claim as my invention: 1. The process of treating fuel'gas, which comprises freeing the compressing the purified gas, coolin the compressed gas to substantially 21311108151 eric temperature, and removing oil mist thereby:

0 gas from tar, ammoma, and other undesirable constituents, 1

formed in the gas by electrical precipita-i tion. l 4,

2. Theprocess ofconditioning fuel containing gum-forming constituents for '8- tribution, which comprises removing from the gas, com ressing the gas to the pressure required the gas, and subjectingthe gas to the influonce of anelectrical discharge to removeoily mlst formed by compression and coo thereby preventing the de osition of gum from the gas during distribution.

3. The process of treating fuel gas to preor distribution, cooling tar.

rent the d'egoelh' Ton" of gumslbr therefro'm,whi h comprises comp th'egaa. flu; a gaug'e'pr ofabo {:20 pounds peru square inch, coo1ing the co p' gas to I. substantially. atmospheric temperature" to cause oily material carried-by'the gas to 3pc in the'form of'amist, and sulnectmg i gastothemflue nqe -.of an electrical discharge'to efiectu-preclpl J0; tation ofsaid oily e Y I. 4. The rocess of treating fuel gas-to pro-- vent the eposition-of gums or teams ere-- from, which comprises removing constituents condensible at ordinary temperatures and '15. pressures, compressing thegastoa ressure 3 Q 1 'materially 'above atmospheric,"coolm thecomp gas tosubstantially atmosp temyfisrature to cause oil material carried bylt to .ap rin eiormof'amist Ill-and s'u iecting c cooled, com ressed gas to the influence of an electrical. arge to. efiect precipitation of said oily n In testimony whereof, I have. hereunto subscribedmy name this, 8rd {day'of August 

